Dense and green cities

Accessibility to green areas in Gothenburg. Illustration: Meta Berghauser Pont, Chalmers Architecture

The importance of green connections

Politicians, architects and researchers have embraced higher urban densities to arrive at more sustainable cities that provide good public transport and create an urban buzz with services at close distance to all. There is, however, a backside to this process of ongoing densification where especially green areas are threatened. They disappear and get more fragmented which make cities a more hostile place to live in for many different species. It is therefore of high importance to include urban greening when densifying cities. The research project presented here is dealing with just that.

When studying green areas and the role they can play for both people and other species in cities, two aspects are important. Firstly, the quality of the green areas in themselves and its maintenance. Secondly, the connections between green areas with so called dispersal corridors. This is especially important when green areas are highly fragmented as is the case in cities. We are well equipped when it comes to the quality of green areas. We know which surface provides us with what service and we have planning tools to regulate the losses of green areas due to densification. The recipe is simple and straightforward: intensify and diversify the green areas so that these can produce a variety of ecosystem services from pollination and water storage to recreation. Even roofs and facades can and should be used.

We know far less when it comes to the connections between green areas. What we do know is that this is of high importance for the survival of birds, insects and other species. Small green areas are vulnerable for disturbances and it is found that for instance bee diversity decreases when there are no other green areas nearby. Instead of thinking in one green roof here and a park there, we have to start thinking about unified green structures. A pocket park or green courtyard can then suddenly play a crucial role in connecting two larger parks that otherwise would have been disconnected for a bee not able to overcome the distance between them.

This research project, a cooperation between Chalmers, SLU and the Beijer Institute will contribute to the understanding of green connectivity and the development of a tool to implement this knowledge in urban design projects. Densification projects should not only compensate for the green they occupy with buildings, but they should start contributing to the green structure that connects urban green areas to the surrounding green landscapes. Only then can we talk about sustainable cities that are both green and dense.

Published: Fri 27 May 2016.